Cellular ceramics apparatus and methods of production

ABSTRACT

Cellular ceramic materials, for example closed cell glass ceramic materials, for use in construction of buildings comprising a clay material, carbon, and water used to form the cellular ceramic blocks, slabs and beams by expansion of the particles inside the ware. The cellular ceramic materials are produced by first mixing the clay, carbon and about 40% to about 70% water by weight of the clay in the mixture, allowing the mixture to cure, drying the cured mixture, then firing the dried mixture at a temperature and for a period of time sufficient to melt the surface of the mixture. The clay material can be, for example, surface clays, ball clays, kaolin, shale, fly ash and/or bentonite. In another embodiment a mixture of volcanic ash, carbon and water can be formed and layered with the mixture of clay, carbon and water. The cellular ceramic materials are, in most cases, impervious to liquid, are capable of supporting substantial loads in tension and compression without reinforcement, and require no additional insulating material. Such cellular ceramic material may also be used in the construction of buildings with a metal skeleton comprising metal bars forming a structure for supporting the cellular ceramic building material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/048,962 entitled “CELLULAR CERAMICS APPARATUS AND METHODS OFPRODUCTION” filed on Mar. 16, 2011 and claims the benefit of andpriority to U.S. Provisional Patent Application No. 61/314,442, filedMar. 16, 2010 entitled “CELLULAR CERAMICS APPARATUS AND METHODS OFPRODUCTION”, the contents of all of which are incorporated by referenceas if fully set forth herein.

FIELD OF THE PRESENT DISCLOSURE

The invention relates generally to materials used for buildingconstruction and methods for making building materials, in particular tocellular ceramic building materials, and more specifically to cellularglass ceramic building materials and methods of making cellular glassceramic building materials.

BACKGROUND

Since 1945, and particularly in the 50's and 60's, there have beenefforts to develop a cellular ceramic building material from abundantnatural resources, with apparatus and methods for continuous production.The cellular glass blocks on the market since about 1945 initiallylooked like an acceptable material, but had some drawbacks, includingpractically no value for protection from fire, and the shapes beingextremely friable. Further, the starting material for cellular glassblocks is a borosilicate glass, which is an expensive raw material. Thisresults in a prohibitive cost for heavier and more rugged buildingblocks.

Certain raw materials, including clays and sands, may be used that areless expensive and found in various areas of the surface of the earth.Other less expensive materials such as fly ash produced as a by-productof manufacturing facilities, from the burning of coal, and trash may beconsidered and mixed in certain proportions. These cheaper materials maybe used to form ceramic blocks, slabs and timbers; however, they requirecontainers of a lesser temperature resistance than the metal alloys usedfor existing cellular glass blocks. In order to achieve economies ofscale and incur minimal material handling costs, materials may beprocessed in very large quantities requiring significant amounts of heatgeneration. The existing tunnel kilns used for processing of suchmaterials into ceramic blocks recuperate heat from the flue gas and fromthe burden (the ware plus the means of containing and supporting in theheat). Presently, the primary air for combustion is brought to theburner at ambient temperature, and a large portion of the fuelconsumption is for heating the air to the flame temperature. This leadsto large energy consumption costs during the forming process. If the airwere introduced into the burner at a high temperature, it would igniteprematurely and unsafely.

One attempt to form cellular blocks is described in U.S. Pat. No.4,212,635. This patent describes a process in which clay or silica canbe mixed with a small amount of soluble carbonaceous material and waterto adjust the carbon and moisture content of the clay or silica with thecarbonaceous material and water. This mixture is then fired in a kiln toproduce a cellulated vitreous refractory material. We have found itdifficult to produce suitable product using the teachings of thispatent. For example, when using bentonite we had to make a number ofchanges to the process described in this patent in order to formsuitable product, including but not limited to changes in theformulation and changes in the manner in which the formulation is mixed,dried and fired in order to produce a suitable closed cell ceramicmaterial product.

SUMMARY

In one embodiment of the present disclosure an expanded closed cellproduct is formed, having use for example as a construction material.The closed cell material is a closed cell ceramic material comprisedprimarily of clay and carbonaceous material. In a particular embodiment,a closed cell glass ceramic material is formed. The clays which havebeen found to be useful include but are not limited to surface clays,ball clays, kaolin, shale, and bentonite. By surface clays we mean claysmined from the Earth's surface as opposed to surface treated clays.Other clays which are useful for the process will have an ultimateparticle size of less than 2 microns, and the ability to sinter into amass of designated size and structure determined by the desired endproduct. Some of these naturally occurring clays, found in rock form,may require crushing to a maximum size capable of passing through a 4mesh screen, typically 0.2 inches or less in diameter. Larger particlesmay be added for strength or density, however, dependant on the desiredproduct. Many organic clays containing carbon may be used provided thecarbon is water soluble and will char upon heating. Preferably, theamount of naturally occurring carbon should not exceed the limitsdiscussed below. In the event that the carbon content in the organicmaterial is less than the desired total amount, carbon can be added.Most any form of carbon can be added that is water soluble and will charupon heating. Suitable forms of carbon include water solublecarbohydrates. Other suitable forms of carbon include carbon black andnaturally occurring carbons in surface clays.

In an embodiment of the present disclosure, the expanded closed cellceramic material product, for example a closed cell glass ceramicmaterial product, is formed from a mixture of clay material, carbon andwater. In one embodiment of the present disclosure, the expanded closedcell ceramic material product is formed from a fine mesh clay (thedesired mesh dependant on the solubility of the clay in water). The clayis mixed with about 0.5% to about 2.5% carbon and about 40% to 70%water, these percentages being percent by weight of the clay in themixture or parts per 100 parts of clay. A suitable clay is bentonitecomposed of about 60% to about 80% silicon dioxide, about 14% to about26% aluminum oxide, about 2% to about 6% magnesium oxide and 0% to about11% iron oxide. A preferred fine mesh for the clay is 325 mesh,typically 0.0017 inches or less in diameter. In another embodiment theclay can be a mixture of mesh sizes, for example some being fine meshand some not fine mesh having a maximum size of 4 mesh. Where the clayalready includes some carbon in its natural state the amount of carbonto be mixed with the clay can be adjusted so the combined total amountof carbon in both the clay and mixed in with the clay is about 0.5% toabout 2.5% by weight of the clay without carbon.

In one embodiment the closed cell ceramic product of the presentdisclosure is formed by mixing the clay material, carbon and water,allowing the mixture to cure, then drying the mixture, and finallyfiring the mixture, for example in a kiln. In one embodiment the closedcell ceramic product of the present disclosure is formed by mixingbentonite, carbon and water to form a mixture of the same which mixtureis then allowed to cure, dry and finally fired. In a further embodiment,fly ash is added to bentonite, carbon and water to form said mixture. Inyet another embodiment a mixture of clay, for example bentonite, carbonand water, is mixed and a separate mixture of volcanic ash, carbon andwater is formed and layered with the mixture of clay, in particular,bentonite, carbon and water, one on top of the other.

In another embodiment of the present disclosure, the various ingredientsto form the desired mixture or mixtures are thoroughly mixed together,the aforesaid mixture or mixtures formed into a shape and then allowedto cure for a period of about 4 to about 10 hours, for exampleovernight. Preferably the mixture or mixtures are mixed and cured for aperiod of time sufficient to allow dissolved carbon and water topermeate throughout the mixture(s). In one embodiment, a fine meshcarbon material of 4 mesh or smaller, for example 325 mesh or smaller isused to provide better distribution of the carbon material in themixture and the mixture is cured for about 4 hours to about 6 hours. Thecured material is then dried to drive off excess water, preferably tobring the water composition of the mixture down to a range of about 0.5%to about 6% water by weight. The exact percentage of water in the driedcured material is dependant on material being used in the mixture. Inone embodiment the drying is achieved by forming the cured material intoblocks of about 4 to 5 inches thick and drying the blocks at about 850°F. (454° C.) to about 1000° F. (538° C.), preferably at or around 900°F. for about 4 hours and then allowing the material to cool overnight orlonger, preferably cooling to ambient temperature for handling purposesonly. In a continuous process it would be expected that the cool downstep would be minimal if not eliminated all together by the use of heatresistant equipment to prepare and/or transfer the material for finalfiring. In one embodiment, the drying temperature produces some charringof the carbon in the mixture or mixtures before they are fired.

The dried material is then fired by, for example, placing it in a kilnhaving a reducing environment to a temperature related to the meltingpoint of the dried mixture. Optionally, the dried material may becrushed and re-formed into the final desired shape before firing.Preferably, the reducing environment is such that the SiC in theembodiment when heated to above 2100° F. (1149° C.) and up to 2700° F.(1482° C.) produces SiO₂ and SiO and ½ O₂ are produced and in turnreduced to a gaseous SiO, CO and CO₂. In one embodiment the firingoccurs in a kiln in which the temperature of the kiln is ramped up overa period of about 7 hours or in production as rapidly as possiblewithout damaging the kiln to a firing temperature of about 2350° F.(1232° C.) to about 2550° F. (1399° C.). The firing temperature issometimes also referred to herein as the environment temperature orchamber temperature. This ramp up period may be faster or slowerdepending upon the particular kiln used and also depending upon thetemperature to which the material is cooled after drying the material,if cooled at all. With the right equipment it could be possible to bringthe temperature in the kiln up to the desired firing temperature withinabout an hour or so. Furthermore, the actual time of firing the materialat the desired firing temperature can vary depending upon the density ofthe material to be fired. The material is then held at this temperaturefor a period of time, for example about 15 to about 45 minutes,following which the material is cooled. Preferably, the uppertemperature and the time the material is held at this temperature areselected to be sufficient to melt only the surface of the mixture andnot the interior of the mixture. In one embodiment, the object of thefiring temperature is to sinter the surface of the material and to avoidmelting the entire material.

In one embodiment the cooling takes place in the kiln, after the kilnhas been turned off, over an extended period of time of about 10 toabout 15 hours, or until the interior temperature of the kiln reachesabout 300° F. (149° C.). The product is then removed from the kiln andallowed to further cool to room temperature. The final product resultsin expanded closed cellular ceramic material which may be cut or trimmedto desired dimensions. In a continuous production environment thematerial could be immediately cooled and processed to desired sizes. Thecooling should not occur so quickly, however, as to create fissures orcracking in the material or other structural degradation.

According to certain embodiments of the present disclosure the processof forming cellular ceramic blocks comprises allowing fuel to burn inthe open combustion space and the useful heat transfer can absorb highrates of heat generation. For instance, a theoretical flame temperaturemight be 5,000° F. (2760° C.), but in steady state the combustion zoneor chamber is maintained at 3,300° F. (1816° C.), and the radiant heattransfer to the ware at a heat sink temperature of about 3,110° F.(1710° C.), has a regulating effect and defines the heat transfercapacity and fusion in pound per hour. The melting and heat sinktemperature of 3,110° F. (1710° C.) is for silica or kaolin. For thepreferred pure clay or for fly ash, which have a less pure silicacontent, a much lower fusion temperature would allow the radiant heatblanket to be comfortably below the 3,300° F. (1816° C.) capacity of theaffordable refractory, but a higher combustion chamber temperature (T₁)minus heat sink temperature of the ware or product (T₂) for high ratesof production. Running the conveyor faster in such instances preventsoverheating.

Certain embodiments of the present disclosure produce cellular ceramicbuilding blocks, for example closed cell glass ceramic building blocks,for use in construction of buildings comprising clay, carbon, and waterused to form the cellular ceramic material comprising ware. The cellularceramic material is preferably impervious to liquid, is capable ofsupporting substantial loads in tension and compression withoutreinforcement, and requires no additional insulating material. Suchcellular ceramic blocks may be used in the construction of buildings,preferably with a metal skeleton comprising metal bars forming thebuilding for supporting the cellular ceramic building blocks. The metalskeleton provides additional resistance to tensile and compressiveforces. The metal skeleton may preferably be formed from metal barsinserted in grooves formed in the cellular ceramic blocks. In some casesof short lengths, the ceramic member may not need reinforcement. In longmembers the reinforcement is provided to resist deflection, not forstrength. The steel therefore, is designed to carry the full load,allowing use of a light density cellular ceramic building material insuch construction. Light density materials result in cost savings and amuch better insulation R factor. A fire duration time and temperature isspecified for steel protected by specified thickness of concrete.Similar curves specifying fire duration time and temperature may bedeveloped for cellular ceramics. Preferably the scheme is to installsteel bars in deep grooves and fill with concrete.

Certain embodiments of the present disclosure provide a process forproducing ceramic building materials, for example closed cell ceramicbuilding materials, comprising placing raw materials comprising clay,carbon and water in a container located on a continuous conveyor. Theconveyor may preferably comprise an insulating block, the containerbeing resistant to high temperatures and capable of transporting rawmaterials from an entrance tunnel through a combustion zone and an exittunnel of an exemplary kiln (see, for example, FIGS. 2 and 3). Thetemperature is increased as the raw material passes through the entrancetunnel towards the combustion zone and preheating the raw materials withflue gas from the combustion zone when in the entrance tunnel. Ambientair may be drawn into the combustion zone through an induced draft fanlocated near the entrance tunnel to promote combustion in the combustionzone. The conveyor moves the raw materials through a gas blanket insidethe combustion zone providing radiant heat transfer to the raw materialand heating the raw materials slightly beyond the melting point of thesolid portions of the raw materials. The melting point of some clays isroughly 2400° F. (1315° C.) and the temperature (T₁) inside thecombustion zone is preferably maintained slightly higher to maintain aheat sink temperature (T₂) at about the melting point of the claymixture entering the kiln.

Thermocouples may be placed throughout the entrance tunnel, combustionzone and exit tunnel to monitor the temperature of the various regions.Gas jets located inside the combustion zone may provide natural gas tothe combustion zone, fueling combustion. The conveyor moves the meltedraw materials through the exit tunnel, allowing the raw materials tocool and form a monolithic slab. Ambient air may be pulled through theexit tunnel, passing over the melted materials and drawing heat from thematerial, inducing cooling and slab formation. This heated air may thenbe reclaimed and fed to the combustion zone to further promotecombustion. In one embodiment, this reclaimed heated air can beintroduced into the preheat chamber of the kiln, while at the same timeintroducing gas into the combustion chamber for a controlled efficientburn. The monolithic slab may be cut to the desired shape and sizebuilding blocks after cooling and are thus produced in an energyefficient manner using recuperated heat generated by the process.

Density and surface effects of the cellular ceramic blocks and or slabsaccording to certain embodiments of the invention may vary according tothe type of construction intended. By means of common shaker box andcompaction equipment, for example, quantities of various compositions ofraw materials and of granular sizes can be spread in uniform thicknessin various strata to control densities, in combination with carbonloading and depletion, etc. The surface appearances may be left natural,as affected by particle size of the clay, shape, composition, and firedcolor, etc. More generally, the ware may be configured to a flat surfaceor in decorative patterns and false joints as desired.

Fabrication of the desired cellular ceramic blocks, whether by sawingmotion, shearing, scraping or hole punching, is preferably accomplishedby bending and breaking of the cell walls, not by cutting with a sharpedge. The sawing motion not only applies force in more than onedirection, but also rakes out the detritus of broken cell walls. A sawis immediately dulled in a few minutes work, but with foam glasscontinues to “cut” until the roots of the original chill hardened teethare worn down to a faintly visible indication of the original base.(This would lead to a practice of using cheap metal cutting band sawblades until they are worn out). Costs may be balanced between cheapsaws of high-carbon steel versus longer lasting and more expensive andmore abrasion resistant replaceable teeth. Early trials seem to confirmthat costs and production rates to fabricate ceramic timber and ceramiclumber compare favorably to rates for wood products.

Appropriate tools may be mounted on the conveyor frame moving a slab orblock in a straight line, in order to dress a slab to dimensions, andother tools mounted to provide grooves in which to insert steel bars,and other tools to provide ornamental grooves, fluting, and simulatedmortar joints, most of the tools being stationary, as the work moves.

Cellular ceramic building materials are preferable to conventionalbuilding materials such as concrete for various reasons, including costsavings. The raw material for cement, clay and limestone, costs aboutthe same, per ton, and the cost to grind the clay and limestone rawmaterial, melt to clinker, and grind the clinker to powder, iscomparable to the cost per ton of producing ceramic timber. By roughestimate, a yard of concrete coming off the truck costs more than$100.00 and weighs nearly 3500 pounds. One yard of ceramic timber weighsabout 600 pounds and cost to manufacture and deliver is less than$44.00.

The cost of form work and of placing steel and concrete, and finishingshows comparable cost discrepancies. The designer and builder haveadditional opportunities for cost savings and added values. When anexterior wall or roof deck is erected from cellular ceramic buildingmaterials, it is already insulated better than common practice whereinsulation has been added. This also saves original and future roofing(and brickwork or siding and framework for the walls), for protectingthe insulation. The above comparison is with concrete. The cost savingsmay be slightly less, compared with wood frame construction, but stillsubstantial savings exist when compared to structural steel framing infire resistant construction.

Accordingly it is an object of the present disclosure to provide acellular ceramic material, for example a closed cell glass ceramicmaterial, suitable for use as a building material and method of makingsuch material.

It is a further object of certain embodiments of the present disclosureto provide a system of material preparation, heating, and harvesting, inorder to produce a product substantially cheaper than conventionalbuilding materials and having suitable properties for building elements.

It is a yet another object of certain embodiments of the presentdisclosure to provide a superior system of building design andconstruction employing the expanded closed cell ceramic productdescribed herein.

Other systems, devices, features, and advantages of the disclosedcellular ceramic materials and methods of making said materials will beor will become apparent to one with skill in the art upon examination ofthe following drawings and detailed description. All such additionalsystems, devices, features, and advantages are intended to be includedwithin this description, are intended to be included within the scope ofthe present disclosure, and are intended to be protected by theaccompanying claims.

BRIEF DESCRIPTION OF DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following figures. The components in the drawings arenot necessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views. While exemplary embodiments are disclosedin connection with the drawings, there is no intent to limit the presentdisclosure to the embodiment or embodiments disclosed herein. On thecontrary the intent is to cover all alternatives, modifications andequivalents.

FIG. 1 is a flow chart showing a process according to certainembodiments of the invention.

FIG. 2 is a top view of a kiln according to certain embodiments of thepresent disclosure.

FIG. 3 is a side view of a kiln according to certain embodiments of thepresent disclosure.

FIG. 4 is a front view of a kiln according to certain embodiments of thepresent disclosure.

FIG. 5 is a perspective view of a portion of a kiln according to certainembodiments of the present disclosure.

DETAILED DESCRIPTION

Disclosed herein are various embodiments of cellular ceramic materialsand methods of making said materials. Reference will now be made indetail to the description of the materials and embodiments asillustrated in the drawings, wherein like reference numbers indicatelike parts throughout the several views. While several embodiments aredescribed in connection with these figures, there is no intent to limitthe present disclosure to the embodiment or embodiments disclosedherein. On the contrary, the intent is to cover all alternatives,modifications, and equivalents.

The expanded closed cellular ceramic material and method of making thematerial of the present disclosure overcome the above describeddisadvantages. In one embodiment, the expanded closed cellular ceramicmaterial of the present disclosure is formed from a mixture of a claymaterial, carbon and water which components are mixed and the mixtureallowed to cure. In a particular embodiment a closed cell glass ceramicmaterial is formed. The cured mixture is then dried. After drying, themixture is fired, for example in a kiln, such as described below, for aperiod of time and over a temperature range so as to produce an expandedclosed cellular ceramic product which is then cooled and after coolingmay then be cut or trimmed to the desired measurements.

Suitable clay materials include surface clays, ball clays, kaolin,shale, and bentonite. Clays suitable for forming the present closedcellular ceramic material preferably are presented in particle form andhave a particle size capable of passing through a 4 mesh screen,typically 0.2 inches or smaller. Naturally occurring clays, for example,those formed in rock form may require crushing to attain the preferredparticle size.

In another embodiment, the clay material is a fine mesh clay material.An exemplary mesh is 325 mesh. An exemplary clay material is bentonitehaving about 60% to 80% silicon dioxide (SiO₂), about 14% to about 26%aluminum oxide (Al₂O₃), about 2% to 6% magnesium oxide (MgO) and 0% toabout 11% ferrous oxide (Fe₂O₃). About 100 pounds of the fine mesh claymaterial can be mixed with about 0.5 to 2.5% carbon and about 40% to 70%water per 100 pounds or parts of clay material.

In another exemplary embodiment, the clay material need not be all 325mesh. It can be a mixture of mesh sizes, some fine mesh of about 325mesh and some larger mesh, for example, 4 mesh or smaller.

In another exemplary embodiment of the present disclosure, the expandedclosed cell ceramic material of the present disclosure is formed bymixing the carbon into warm water until fully dissolved. The carbonmixture or solution is then combined with the clay material in a fashionto dampen the entire mixture of clay and carbon while being agitated andfolded until thoroughly mixed. The mixture is then allowed to cure, forexample, by covering the mixture with plastic and allowing to cureovernight.

In one embodiment, a suitable carbon material is a form of carbon thatis water soluble and will char upon heating. Exemplary carbon materialsinclude water soluble carbohydrates. Other suitable carbon materialsinclude carbon black and naturally occurring carbons in surface clays.Preferably the carbon material is mixed with the water and that claymaterial and cured for a period of time to allow dissolved carbon andwater to permeate throughout the mixture. In one embodiment, the curingtime may be about 4 to about 10 hours. The curing time may be dependent,however, on the size and shape of the wet mixture. In another embodimentthe mixture may be cured for about 4 hours to about 6 hours.

The cured wet mixture is then dried, for example, by placing it in akiln to drive off excess water. An exemplary drying temperature is inthe range of about 850° F. (454° C.) to about 1000° F. (538° C.).Preferably the drying temperature also produces some charring of thecarbon in the mixture before the mixture is fired. In an exemplaryembodiment the cured wet mixture is formed into blocks of about 4 to 5inches thick and dried at or around 900° F. and held at that temperaturefor a period of time, for example, for about 4 hours. The dried materialmay then be allowed to cool to ambient temperature. This cooling step,however, is convenient for handling the dried mixture and transferringit to the firing equipment and may be eliminated where heat resistantequipment is available to transfer the dried mixture directly to thefiring equipment.

Firing of the dried material can take place in a kiln, such as describedbelow. The dried material can be placed on high temperature trays, withfor example parting material on the sides and bottoms of the trays. Inone embodiment, the dried mixture may be crushed and loosely packed inthe trays to a desired depth, for example 3 inches, and at whateverwidth is desired upon completion. The kiln is then fired to establish areducing environment. In one embodiment the environment or firingtemperature of the kiln is directly related to the melting point of themixture to be fired. An exemplary firing temperature is in the range ofabout 2350° F. (1232° C.) to about 2550° F. (1399° C.). The kilntemperature can be ramped up over a period of time, for example, about 7hours, to reach the desired peak temperature. This ramp up period may befaster or slower depending upon the particular kiln used. The ramp upperiod will be less if the dried material is not cooled but insteadtransferred directly to the kiln. The ramp up of the temperature shouldnot be so fast as to damage the kiln. When the mixture reaches thedesired melting temperature, the kiln environment ramp up temperature isslowed to maintain a constant product and temperature environment. Inone embodiment the desired peak firing temperature is sufficient to meltonly the surface of the shaped mixture and not the interior of themixture. The object of the firing peak temperature is to sinter thesurface of the material mixture and to avoid melting the entire mixture,in particular the interior of the mixture. An exemplary sintering periodis about 15 to about 45 minutes at this kiln environment temperature,after which the kiln burners are extinguished and the product and thematerial may be cooled in the kiln.

In one embodiment the kiln is allowed to cool for about 10 to about 15hours or until the interior temperature of the kiln reaches 300° F.(149° C.). The fired material product is then removed and allowed tocool to room temperature. The final expanded closed cell ceramic productmaterial may then be cut or trimmed to desired measurements. In oneembodiment, a closed cell glass ceramic product material is formed.

The above described process for preparing the expanded closed cellceramic material of the present disclosure is a batch process. Theprocess for preparing the present material need not be limited to abatch process and may also include continuous processes. In an exemplarycontinuous process, for example, the dried mixture may be transferreddirectly into a kiln without cooling the dried mixture. Further, in acontinuous process, a ramp up period for bringing the kiln temperatureup to the desired peak temperature would not be needed. In analternative embodiment, for example, a kiln might be provided havingsequentially increasing temperature zones, leading to a temperature zonemaintained at the desired peak temperature, using suitable heatresistant conveying equipment to transfer the material through the kilnand to a cooling station and ultimately to a cutting or trimmingstation.

According to certain embodiments of the present disclosure, the presentcellular ceramic material is produced using a kiln such as thatillustrated in FIGS. 1-5. The exemplary kiln 10 is provided with acontinuous container 15 comprised of separate lengths of metal troughs,also referred to as product troughs, with a flange 20 turned up on eachof two opposite sides, and one edge turned down for a flange for a sandtrap, moves on a conveyor. The lengths of the trough are rigidly coupledwith a coupling device which can be disengaged. Inside each flange 20 isa wall of insulating refractory material 40, such as a refractoryparting mat. The bottom surface of the trough between the walls is linedwith a substantial thickness of refractory insulation, comprising amonolithic base for the container in which to fuse a monolithic slab ofcontinuous length. Certain embodiments enable continuous progress, orintermittent movement, cutting to length and harvesting without haltingthe movement; also facilitating the measured flow of combustion air andgasses. An alternative procedure is for the raw material feed to beformed into tiles and placed on top of high temperature refractorygrains, which grains serve as the parting material.

In some embodiments, the container is charged with a measured thicknessof the aforementioned dried mixture, which is fused from the top down,leaving a residue of unfused material at the bottom, as a parting, inorder for the product to be harvested. The raw ceramic body may be allin small particles, tiles, or other sizes and shapes limited only by thedesired end result. Heating and cooling is highly recuperative. Byregulating the speed of the material through the kiln, fast heatingthrough a great thickness is effected on the product. Therefore, heatingthe gas blanket to nearly 2400° F. (1316° C.) to 3300° F. (1816° C.),will supply heat to the successive surfaces of active fusion, inproportion to T₁ ⁴ minus T₂ ⁴ where T₁ is the gas blanket temperature inthe kiln and T₂ is the melting point of the ceramic body (as eachsuccessive surface is melted it no longer absorbs radiant heat but theheat passes through to see T₂ in the next surface). The limit on T₁temperature is the limit on the refractory. Much greater heat transferpotentials are available with clay or fly ash than with pure silica. Theheat potential may be increased by high temperatures for T₁.

According to certain embodiments of the present disclosure, as shown inFIG. 1, raw product enters the kiln 10 at the entrance tunnel 35, havingbeen placed into a refractory ware on a continuous plate capable ofproducing the size of finished material desired. It is moved inside thekiln, facilitated by the use of rollers 30 being turned by a variablespeed motor driven chain or through a force created by hydraulic pushrods. The mixture (raw material) enters the preheat zone 2 and absorbsradiant heat 3 drawn from the exhaust of the combustion zone 37 by oneor more draft induced fans 4 which exhaust is ultimately exhausted tothe atmosphere 5, and in some cases auxiliary heaters. Continuing intothe combustion zone 37, the mixture forms into a desired material andcontinues into the annealing zone 6. The heat can be maintained by anauxiliary heater 7 if necessary to control the environment if needed fora specific product. The new product continues to be cooled 8 to a safehandling temperature. While these actions are taking place, ambient orenvironmental air 9 is being drawn into the products exit end of thetunnel 39 by a variable speed fan located at the entrance of the tunnel35. This fan speed is matched to the amount of air required in thecombustion zone 37 and the amount of fuel, for safe stoichiometric airto fuel ratio (AFR) for safe combustion. As the air comes into thetunnel it is warmed 11 by the heat of the new product. When entering thecombustion zone 37 the air is above 1500° F. (816° C.). It will then mix38 with the fuel being fed into the chamber with regulated nozzles for aspontaneous ignition. Care must be taken to have correct mixturesavailable for the combustion zone area. Each product requires adifferent set of parameters for correct heat sink features. The exhaustair continues toward the draft fan 4, warming the raw material and isforced out into the atmosphere through proper exhaust vents 5.

According to certain embodiments of the present disclosure, where bottomheat is desirable, refractory plates may be supported by posts on acontinuous container built to be heated somewhat as in a conventionalkiln, except that the more full recuperation of the heat is utilized,FIG. 1, and optionally the long and continuous lengths are produced.

A stack furnace may be provided, somewhat similar to a burn-out furnace.A conveyor 28 preferably feeds into the stack furnace. The conveyor issupported by rollers 30 dispersed along the length of the kiln. Thestack furnace is useful in burning out the excess carbon in fly ash, ifused, and supplying useful heat to the kiln line. The stack furnace maybe substituted for a major portion of the pre-heat section of the kilnline. Loading the container at some distance from the combustion chamberallows some cooling of the flue gasses, preventing overheating andstickiness to impede pouring and leveling of the raw materials.

Certain embodiments of the present disclosure include methods ofbloating and shaping the plates or slabs of ceramic building material.The gassing and cellulation is explained somewhat in the prior art, butfurther details are pertinent to the extreme sizes in 3 dimensions, andin continuous flow of production. A container may be provided and acharge of the aforementioned dried material leveled to a desired depthwhich flow down a stack or chute to the moving container below, to bescreeded to a specified level by a horizontal bar (not shown), as thecontainer advances along the conveyor, enabled by the pourable shapes ofthe dried material. If necessary the dried material may be crushed torender it flowable or pourable.

In an exemplary method, dried material advances through increasingtemperatures of an environment of flue gasses through an entrance tunnel35. The spaces between the particles of dried material allow thecirculation of flue gasses and consequent transfer of heat, tending toseal the pores of the material, even as the high temperatures tend tocause the water vapor and other oxidizing gasses, to react to provideadditional gasses. Ostensibly, there are stages in the process where thepores are open enough to allow fast escape of gas, so the effect is todeplete the carbon content, with little bloating. At a later stage thepores are so fine that some loss-on-ignition gasses are trapped longenough to become completely sealed in by fusion. Implausible as it mayseem, ordinary gauges allow the repeatability of values over wide rangesof density of the product, well within commercial needs.

According to certain embodiments of the present disclosure, a stackfurnace maintains the flow of dried material, preheated below stickingtemperatures and further heated in the shortened horizontal preheatsection. As the particles in the top layer are heated these particlessoften and expand to form a layer which effectively seals off the top byfilling and welding, eventually filling and welding throughout thethickness. At times, a thick block is found to be expanded andsinter-welded to a monolith, but with slightly permeable cell walls andlacking in the glassy look of the completely fused product. This happenswhen the operating temperature T₁ is insufficient to fuse all thediverse particles to the glassy state, the body remaining essentiallyopaque such as used in the production of alumina silicate bodies whichfoam and mature at about 3300° F. (1816° C.), but useful in service as afurnace liner facing an environment of up to 3600° F. (1982° C.).Certain other clays and embodiments will provide products of the presentdisclosure, as described below.

The present cellular ceramic body or building materials may be preparedby a process involving heating and cooling. The ceramic body is foundwith, or provided with, materials which react upon heating in order toproduce gas. In an exemplary embodiment, the aggregate body may containiron oxide and carbon content, or carbon may be added to reduce orpartially reduce the iron oxide. With bodies of relatively pure oxides,such as silica and alumina-silicas, a small addition of carbon,hydrocarbon, or carbides reacts with silica to produce CO₂. For thepreferred exposure to the products of combustion, the dried material ispelletized or crushed and shaped into units of approximately uniformsizes. As the dried material is measured and poured into the train ofpans, it is leveled to a thickness that will produce the designatedthickness of ware plus sufficient body to remain unfused, in order torelease the ware for harvesting. According to certain embodiments of theinvention a parting layer of mineral granules or grains are providedrather than extra body. The dried material can be shaped into blocks,bricks, flat strips and timbers of various lengths.

Certain embodiments of the present invention allow for the passage ofthe containers through the kiln is enabled by using large containers,capable of presenting the shaped ceramic body in continuous motion,passing though the gas blanket which gasses may include diatomic gasseswhich are highly capable of absorbing and emitting radiant heat. Thecontainer containing raw materials passes through the entrance tunnel 35where it is preheated and enters combustion zone 37. The open housing ofthe combustion zone 37 comprises the gas blanket above. The size of thecombustion zone can be determined by the air to gas ratio for ignitionand temperature. This is the stoichoimetric air to fuel ratio (AFR)desirable for complete combustion. The combustion zone 37 must be largeenough for the raw product to form and cellulate according to the speedof the material as it passes through the combustion zone. Once theignition has occurred the AFR may be adjusted plus or minusapproximately 10% to maintain either a reducing or oxidizing environmentfor proper formation of the product. In FIG. 3, it should be noted herethat the size of the combustion zone 37 may vary in accordance with thematerial and product being desired, the volume of such will also affectthe AFR. FIG. 5 also shows a rather large combustion zone 37 in which alarge gas blanket is desired for formulation of products varying indensity and length. The heat transmitted to the ceramic body rawmaterials is higher with greater gas blanket thickness. If the target ofthe radiation is comprised of crystalline solids, then the ceramic bodyfuses a tiny increment of thickness on the surface of the body, to glasswhich is highly transparent to radiant heat. Silica solids, notablysand, may be fused rapidly with the gas blanket at 3,300° F. (1815° C.),but normally cooled rather fast, in order to prevent the glass fromcrystallizing and having slightly greater thermal expansion, asformulation and heat treatment produce 3% to 8% of very fine crystals,which essentially block radiant heat. With thermal expansion increasedby less than 10% or 0.0000004 inches per inch, kaolin also fires toglass but crystallizes sufficiently in cooling to near minimum thermalconductivity. The rate of heating the ceramic body depends on the gasblanket T₁ ⁴-T₂ ⁴, where T₂ is the melting point of the ceramic body andT₁ is the gas blanket temperature. Increasing T₁ increases the heattransferred to the ceramic body. After the ceramic body gets to themelting point, added heat results in more pounds melted, without rise inthe body temperature. As all the latent heat supplied to an increment ofthickness, the increment becomes glass and the heat passes through tothe raw layer below. The rate of heat transfer will change with T₁, typeof material and other factors. The hand books can be interpreted toconfirm transfer of approximately 20,000 BTU's per square foot per hour.

In the common use of conventional kilns, formed ware is subjected to hotgases, in forced and/or natural convection, with time for heat toequalize throughout thick shapes. The time to dry, fire and cool mayvary from less than 8 hours to more than 6 weeks. In bricks, forinstance, which are stacked high without much separation in the stacksand between stacks, the clay is usually tolerant of variations in timeand temperature. For cellular glass, temperatures and time at specifiedtemperatures are closely controlled, in order to control the density andstrength of the cellular glass.

Ambient air may be drawn into the kiln through exit tunnel 39, thecombustion zone 37, and the entrance tunnel 35 due to the pressuredifferential caused by an induced draft fan located near the opening ofthe entrance tunnel 35. The conveyor moves the raw materials through agas blanket inside the combustion zone providing radiant heat transferto the raw material and heating the raw materials slightly beyond themelting point of the solid portions of the raw materials. In the case ofsilica the melting point of the dried material is roughly 3250° F.(1788° C.) and the temperature inside the combustion zone is preferablymaintained at approximately 3300° F. (1815° C.). Thermocouples may beplaced throughout the entrance tunnel, combustion zone, and exit tunnelto monitor the temperature in the various regions. Gas jets may belocated inside the combustion zone and provide natural gas to thecombustion zone, fueling combustion.

The conveyor 28 moves the melted materials through the exit tunnel 39,allowing the materials to cool and form a monolithic slab. Ambient airmay be pulled through the exit tunnel, passing over the melted materialsand drawing heat from the melted materials, inducing cooling and slabformation. The heated air may than be fed into the combustion zone tofurther promote combustion. The monolithic slab may be cut to thedesired shape and size building blocks after cooling, producing buildingmaterials in a cost effective, energy efficient manner usingrecuperative heat generated by the process.

In certain embodiments of the present disclosure, slabs are, forinstance, 4 feet wide and up to more than 8 inches thick. If thecombustion zone 37 is heated to just above the fusion temperature, itmight take hours to heat the slab almost to the environment temperature,ostensibly producing great variations in density. In some embodiments ofthe invention, highly useful ware may have a designated density withacceptable tolerances, over a great thickness but it will be useful,also, to provide slabs with a small depth of greater density andhardness. Factors that can be varied to some degree and, combined,affect density overall or stratum by stratum.

The proportion of carbon allowed to contact the metal oxide that reactsat the designated temperature is affected by the formula proportions,minus the depletion by premature reaction. Pellets or other shapes andsizes, may be progressively sintered while the flue gas diffuses intothe more accessible surfaces. As the reaction temperatures are reached,and the shape only partially sintered, the carbon is depleted byreaction with any O₂ in the flue gas or by water vapor from the flue gasand from calcining of the body. All is progressive with the temperaturerise. The amount of gas captured, and the resulting density may bedetermined by experiment with the formulation and the firing conditions.

Some embodiments provide a means to fire by convection, without theexcessive temperature of radiant heat firing, by supporting containers,other furniture and ware to leave space above the car top, also raisingthe roof as necessary, making the apparatus act as a conventional kiln;except that essentially all of the combustion air passes over the heatedware, heating the air to a temperature near to the temperature of thekiln. In the conventional kiln, part of the air necessary to cool theware is drawn off to dry the ware in a manner which wastes considerableheat, but avoids preheating the air and causing premature combustion. Inconventional burners, if the fuel gas is mixed with heated air to theburner it causes damaging combustion in the metal burner but when coldair becomes the principle air for combustion, heating air to thecombustion temperature requires more fuel. In using the invention tofire formed ware some of the hot air stream comes under the ware, wheresome of the fuel is injected.

According to some embodiments of the present disclosure, sensors mayprevent delivery of fuel through gas jets except when the air is wellabove the ignition temperature (similar to common safety devices inconventional gas-air firing). It is recommended to provide aconventional gas-air system for start-up and for temperatureirregularity at the end of a run in annealing.

According to some embodiments of the present disclosure the apparatusfor producing ceramic building materials is provided with a stackfurnace, in lieu of the major part of the preheat portion of the tunnel.The dried material is shaped into a form firm enough to resistsignificant abrasion in conveying and feeding. The charge is maintainedin the stack to a designated height. At the bottom of the stack thecontinuous container is moving under the stack's contents, which settleinto the container and are raked off by a screeding bar to a designatedlevel. The container proceeds into a relatively short tunnel, in whichthe flue gas loses some temperature and avoids overheating in the stack(cold air may be injected into the tunnel if deemed necessary).

Particles of the dried material of pourable sizes and shapes can beeasily distributed over a container area of unlimited size. The materialmay be formed of wet or damp mixes with soluble carbohydrates in water.In drying, excess soluble carbohydrate is brought to the surface of anyobject, and deposited. In certain embodiments of the present disclosure,the hot flue gasses tend to react with the carbon before sintering trapsall of the resulting gases. This becomes a factor in experimentalformulation. Preheating is facilitated by convection and radiation tothe large surface areas and short internal distances from the surfacesof the material.

Among the variables in the degree of burnout of carbon are the particlesize and shape of the material and the velocity of the ceramic chargepassing through the process. Pulverized clay as the raw material may beused to form acceptable material for the kiln. For example, to 325 meshclay, add water containing a solution of carbon. The body is formed anddried to produce the material for the kiln. A water solution of carbonblack may provide the desired carbon, but the present example will bewith a carbohydrate solution that will dry and char to leave carbon onthe surface of the particles of the clay. Very fine particles of ceramicraw materials sinter at much lower temperatures than coarse particles,and this may be the means by which particles of carbon are sealed inbefore the carbon silica reaction produces CO₂, with SiO and CO alsobeing held in contact with silica in the clay until the reaction withcarbon is completed to SiO₂ and CO₂.

High melting clays, such as kaolin or fire clay, melt at about the sametemperature as silica, and are fired much the same way. In both thesilica and the clay, excess carbon addition anticipates some depletionof the carbon by infiltration of air and by combustion gases, whichinclude water, which also combines with carbon to produce gases that aremostly dispersed before being trapped by the sintering and fusion. Theamount of gas to be contained in the product can be made sufficientlyrepeatable, for practical purposes.

If the raw material used to produce ceramic building materials is ironbearing surface clay, or the like, the process is similar, except thatthe carbon reduces iron oxide instead of silica, and sinters and fusesand reacts at lower temperatures, fortuitously somewhat compatible, andrepeatable. Fly ash is essentially clay which has been heated anddehydrated. The excess carbon left by firing coal in accordance with airpollution regulations, leaves unburned carbon in the ash, which carbonmay cause excess gassing and unacceptable cellulation in bloating. Otherformations using fly ash in a mixture address the need to remove thecarbon from the surfaces of the particles in order for the ash to beused in concrete and resin mixes. A somewhat similar burn-out occursduring the process of cleaning the fly ash, as burn-out is accomplishedin the preheat stack furnace, with some residue of the carbon leftembedded in the coarser particles of fly ash, or found deeper in themixture.

With some carbon remaining for gasification with controls, somedesirable densities can be achieved in a variety of products using thesewaste materials. The variations in particle size of the carbon contentproduce variations in cell sizes, but these variations may beacceptable. Note that the carbon reaction possibly may be with othermetal oxides found in some earths such as manganese oxides, or byreducing SiO₂ in the mix.

The kiln having elevated carrier plates, preferably commerciallyavailable plates in the available small sizes with 3,760° R capabilityor higher, are elevated on posts 45 to one level, to make one continuousdeck, on each section. On each of the section sized decks, a layer ofceramic particles and a few layers of paper are spread, and a boundaryform placed, to confine a slurry to form a section sized or longerplate, to be dried and fired, but not fused. The slurry may beoptionally foamed and result in a very large insulating deck plate.

In firing, the paper chars and burns, leaving the plate to rest on aparting layer of dry ceramic particles. The resulting plates can be usedto form plates for future kilns, providing the option to produce solidor cellulated plates as wide as the container and as long as one sectionor as a number of sections in train. For example, a mixture of kaolinand alumina may be used to make a plate.

To progress to higher temperatures; firing, but not fusing, carrierplates of zirconia content. The kiln products will be such as highalumina and high zirconia insulating refractories, cellulated by fusingor by aerating the slurry; capable of resisting up to 5,000° R.

In order to make a higher temperature deck plate it is not necessary tocellullate or to fuse. Adequate strength results from firing to thecapability of the first kiln. Likewise the side brick for the containerand the shapes for the tunnel walls and roof can be made at atemperature below their use capability. Cellulating is obtained by: (1)sintering to capture CO₂ gas in firing, or (2) making the body in theform of a slip or slurry and aerate into a foam and then drying andfiring. By these procedures a high alumina class of insulating firebrick can be produced to make a kiln to produce construction material tobuild additional kilns. The high alumina kilns can fire ware of zirconiaup to the kiln's capability. This ware formed as decks, cellulatedshapes for walls and roof can possibly attain a temperature capabilitymuch higher, in the neighborhood of 5,000° R.

Products acceptable for commercial sale as well as for internal uses canbe made as described. If further firing is desired before selling orusing, the ware can be fired to about 5,000° R in the kilns made of theware as described above. This will provide the capability to tryzirconia with a small portion of bonding material, such as kaolin, tocellulate below the melting point of zirconia but by carbon reaction toreduce the kaolin. Up-grades with other refractory ceramics, andcellulation, can be accomplished in this same manner.

After the ceramic materials have been produced, the materials may beformed into blocks as desired. With the penetration of radiant heat,slabs of 8 inches or more in thickness are very practical to produce.Various widths and lengths, are squared up and cut to dimensions, muchas a tree trunk is cut into timber or lumber. Sawing, shearing, planing,punching, etc., are by breaking of the thin walled bubbles, by wearresistant tools, which do not need to be sharp. Fluting, grooves forwiring, and for small pipes, and simulated mortar joints, and decorativedesigns are easily accomplished, by machines or manually.

Raw materials such as kaolin, or other “fire clay”, may be used to makeinsulation boards at about 10% of the present cost per cubic foot ofinsulating fire brick. The same strength and hardness can be achievedwith about half the weight, with the R value (resistance to heat flow)about twice as much as the heavier aerated concrete. Other convenientmaterials, such as iron bearing brick clays and fly ash, of similarstrength, typically cost slightly less, and serve as well, for generalbuilding blocks.

Various factors affect density of the ceramic materials overall and invarious strata, including carbon content of the raw materials. Thesefactors can be controlled to make the slab without noticeablevariations; but a dense surface stratum on a low density slab may easilybe achieved.

Typically, the block or slab is formed by the expansion of the materialparticles filling any open spaces between the particles and pushingagainst the sides, while pushing upward to increase the thickness ofware. The expansion occurs as (1) gases are generated by the reaction ofcarbon heated in contact with a metal oxide (2) as the temperature risesthe particles with finer particle sizes sinter first, which slows theescape of gas and traps some gas. Ideally, all cells will finally besealed completely, but near perfection and a less shiny, glassy look andsome permeability is accepted for high temperature service. Coatings forappearance and toughness will further insure against damage fromweather. It is usually found that clays with very fine particle sizeswill sinter well, but coarse clays and gritty particles need help fromfine clay or colloidal sized particles, or by solutions of fluxes. Inlieu of coatings the material may also be layered with another claymaterial for strength, density and looks, or glazed for color andeffect.

These expedients have been found to give good variability andrepeatability with ordinary commercial controls of combustion air volumeand process temperatures. With flexibility in loading and formulation,density variations can be manipulated to provide tough surfaces onlightweight interiors (low density for low cost and high insulatingvalue).

Example 1

A cellular ceramic material, in particular a closed cell glass ceramicmaterial, of the present disclosure was made by 1) mixing bentonite,carbon and water, 2) curing the mixture, 3) drying the cured mixture,and 4) then firing the dried cured mixture. In particular, 100 pounds of325 mesh bentonite were mixed with 1.5% carbon and about 50% to about60% water per 100 pounds of bentonite. The carbon was mixed in exactproportions into warm water until fully dissolved. This carbon solutionwas mixed with the bentonite in a fashion to dampen the entire mixturewhile being agitated and folded. The resultant material mixture wascovered with plastic and allowed to cure overnight.

The cured wet material was placed in the above-described kiln. The kilntemperature was gradually ramped-up from ambient temperature at a rateof 300 degrees per hour. When the kiln temperature reached 900° F. (482°C.), the temperature was held for 4 more hours for a total of 7 hours ofdrying, including ramp-up time before turning off and allowing thematerial to cool.

After the material was cooled for handling, the material was placed onhigh temperature trays with parting material on the sides and bottom ofthe trays. The material was loosely packed in the trays to a depth ofthree inches at whatever width was desired upon completion. The kiln wasturned on to ramp-up to 500-550° F. in the first hour. The kiln was thenregulated to a controlled ramp of 250° F. per hour for 6 hours to anenvironment temperature of approximately 2000° F. (1903° C.). The kilnwas then fired to establish a reducing environment, ultimately takingthe environment temperature of the kiln to 2200° F. (1204° C.) to 2800°F. (1538° C.) at a rate of 300° F. to 350° F. per hour. When the heatsink temperature of the material was such that it penetrated the surfaceof the mixture, in the range of approximately 2360° F. (1293° C.) to2450° F. (1343° C.) (as read by an IR temperature gun, with anemissivity setting of 0.95), the kiln environment temperature was slowedto maintain a constant material and environment temperature at a rise ofno more than 45° F. per hour. After about 30 minutes at this kilnenvironment temperature the material was cooled at a rate to insureappropriate and conventional tempering after which all kiln equipmentwas turned off and the kiln was allowed to cool for 10-15 hours, oruntil the interior temperature of the kiln reached 300° F. (149° C.).The material was then removed and allowed to further cool to roomtemperature outside of the kiln. The final cooled closed cell ceramicmaterial was then cut or trimmed to the desired dimensions.

Example 2

A cellular ceramic material, in particular a closed cell glass ceramicmaterial, of the present disclosure was made by 1) mixing bentonite, flyash, carbon and water, 2) curing the mixture, 3) drying the curedmixture, and 4) then firing the dried cured mixture. In particular, 75pounds of 325 mesh bentonite and 25 pounds of fly ash were mixed with1.0% carbon and about 50% to about 60% water per 100 pounds of mixture.The carbon was mixed in exact proportions into warm water until fullydissolved. This carbon solution was mixed with the bentonite and fly ashmix in a fashion to dampen the entire mixture while being agitated andfolded. The resultant material mixture was covered with plastic andallowed to cure overnight.

The cured wet material was placed in the above-described kiln. The kilntemperature was gradually ramped-up from ambient temperature at a rateof 300 degrees per hour (149° C. per hour). When the kiln temperaturereached 900° F. (482° C.), the temperature was held for 4 more hours fora total of 7 hours of drying, including ramp-up time before turning offand allowing the material to cool.

After the material was cooled for handling, the material was placed onhigh temperature trays with parting material on the sides and bottom ofthe trays. The material was loosely packed in the trays to a depth ofthree inches at whatever width was desired upon completion. The kiln wasturned on to ramp-up to 500-550° F. in the first hour. The kiln was thenregulated to a controlled ramp of 250° F. per hour for 6 hours to anenvironment temperature of approximately 2000° F. (1903° C.). The kilnwas then fired to establish a reducing environment, ultimately takingthe environment temperature of the kiln to 2200° F. (1204° C.) to 2600°F. at a rate of 300° F. to 350° F. per hour. When the heat sinktemperature of the material was such that it penetrated the surface ofthe mixture, in the range of approximately 2250° F. (1232° C.) to 2380°F. (1304° C.) (as read by an IR temperature gun, with an emissivitysetting of 0.95), the kiln environment temperature was slowed tomaintain a constant material and environment temperature at a rise of nomore than 25° F. per hour. After about 30 minutes at this kilnenvironment temperature the material was cooled at a rate to insureappropriate and conventional tempering after which all kiln equipmentwas turned off and the kiln was allowed to cool for 10-15 hours, oruntil the interior temperature of the kiln reached about 300° F. (149°C.). The material was then removed and allowed to further cool to roomtemperature outside of the kiln. The final cooled closed cell ceramicmaterial was then cut or trimmed to the desired dimensions.

Example 3

A cellular ceramic material, in particular a closed cell glass ceramicmaterial, of the present disclosure was made by 1) mixing bentonite,carbon and water, 2) mixing volcanic ash, carbon and water, 3) curingthe mixtures, 4) drying the cured mixtures, 4) compacting and layering(one on top of the other) the dried mixtures, and 5) then firing thedried, cured, doubled layered, mixtures. In particular, 50 pounds of 325mesh bentonite were mixed with 1.5% carbon and about 50% to about 60%water per 100 pounds of bentonite. Also, 50 pounds of 325 mesh volcanicash were mixed with 1.5% carbon and about 50% to 60% water per 100pounds of volcanic ash. The carbon was mixed in exact proportions intowarm water until fully dissolved. This carbon solution was mixedseparately with the bentonite and volcanic ash in a fashion to dampenthe entire mixture while being agitated and folded. The resultantmaterial mixtures were covered with plastic and allowed to cureovernight.

The cured wet materials were placed in the above-described kiln inseparate containers. The kiln temperature was gradually ramped-up fromambient temperature at a rate of 300 degrees per hour (149° C. perhour). When the kiln temperature reached 900° F. (482° C.), thetemperature was held for 4 more hours for a total of 7 hours of drying,including ramp-up time before turning off and allowing the material tocool.

After the material was cooled for handling, the bentonite material wasplaced on high temperature trays with parting material on the sides andbottom of the trays, packed and layered with the volcanic ash. Thematerial was packed in the trays to a total depth of 4 inches (2 inchesper layer) at whatever width was desired upon completion. The kiln wasturned on to ramp-up to 500-550° F. in the first hour. The kiln was thenregulated to a controlled ramp of 250° F. per hour for 6 hours to anenvironment temperature of approximately 2000° F. (1903° C.). The kilnwas then fired to establish a reducing environment, ultimately takingthe environment temperature of the kiln to 2200° F. (1204° C.) to 2800°F. (1538° C.) at a rate of 300° F. to 350° F. per hour. When the heatsink temperature of the material was such that it penetrated the surfaceof the mixture, in the range of approximately 2360° F. (1293° C.) to2450° F. (1343° C.) (as read by an IR temperature gun, with anemissivity setting of 0.95), the kiln environment temperature was slowedto maintain a constant material and environment temperature at a rise ofno more than 25° F. per hour. After about 30 minutes at this kilnenvironment temperature the material was cooled at a rate to insureappropriate and conventional tempering after which all kiln equipmentwas turned off and the kiln was allowed to cool for 10-15 hours, oruntil the interior temperature of the kiln reached 300° F. (149° C.).The material was then removed and allowed to further cool to roomtemperature outside of the kiln. The final cooled closed cell glassceramic material consisted of two closed cell materials completely fusedtogether into one material of varying densities. It was then cut ortrimmed to the desired dimensions.

The closed cellular ceramic materials of the present disclosure aredesirable for use in building construction. The new system of design isbased on the hard sciences of structural design. An example is arequirement of steel bars in both tension and compression with beamscalculated to be strong in tension and compression, but deflection isfar in excess of concrete standards. This calls for steel rebars to bearthe loads in compression and tension in order to stiffen the steel. Thiscan allow very light cellulated ceramic, as steel carries the load.Rebars can be up to 4 feet or more apart in long spans and no steel forshort spans between the long bars.

The raw materials of cellular ceramics, like those for concrete, aresurface (pit mined) materials, abundant in most areas of most states andcountries. The cost per ton is intuitively, minimal for either product.

The use of closed cellular ceramic material as a building materialprovides other advantages as well. For example, cellular ceramicmaterials require no additional protection from insulation board, or anyadditional layer of bricks, stucco, or siding to cover the insulation.The new product itself has an R value greater than 0.25 per inch ofthickness. The surface, as fired, may give various pleasing looks, orthe ceramic timber may be shaped and given stucco effects, or the lookof brick and stone, or painted, or given groves and fluting andsimulated joints by normal material tooling equipment. When certainmaterials are layered, they can produce different types of strength,density, R values, and desirable surfaces for many applications.

It should be emphasized that the above-described embodiments of thepresent disclosure are merely possible examples of implementations setforth for a clear understanding of the principles of the disclosure.Many variations and modifications may be made to the above-describedembodiment(s) without departing substantially from the spirit andprinciples of the disclosure. All such modifications and variations areintended to be included herein within the scope of this disclosure andprotected by the following claims.

Therefore, at least the following is claimed:
 1. A method of producing aclosed cell ceramic material product comprising the steps of: a)providing clay, carbon and water; b) mixing the clay, carbon and about40% to about 70% water by weight of the clay in the mixture to form amixture of clay, carbon and water; c) allowing the mixture to cure; d)drying the cured mixture; e) firing the dried mixture at a temperatureand held at the temperature for a period of time sufficient to melt thesurface of the mixture; and f) cooling the fired mixture to produce theclosed cell ceramic material product, wherein the carbon is solublecarbon and the combined total amount of soluble carbon in both the clayand the carbon mixed with the clay is about 0.05% to about 2.5% byweight of the clay without carbon in the mixture.
 2. The method of claim1, wherein the clay is selected from the group of surface clays, ballclays, kaolin, shale and bentonite.
 3. The method of claim 1, whereinthe carbon is water soluble and will char upon heating.
 4. The method ofclaim 1, wherein the dried mixture is fired in a reducing environmentsuch that SiC in the mixture when heated to above 2100° F. up to 2700°F. produces SiO₂ and SiO and ½ O₂.
 5. The method of claim 1, wherein themixture is allowed to cure for about 4 hours to about 6 hours.
 6. Themethod of claim 1, wherein the cured mixture is dried to bring the watercomposition in the mixture down to within the range of about 0.5% toabout 6% by weight of the mixture.
 7. The method of claim 1, wherein thecured mixture is dried at a temperature in the range of about 850° F. toabout 1000° F.
 8. The method of claim 1, wherein the clay is a bentoniteand the upper temperature for the firing of the mixture is in the rangeof about 2350° F. to about 2550° F.
 9. The method of claim 1, whereinthe clay is bentonite, fly ash is added to the bentonite, carbon andwater to form the mixture, and the upper temperature for the firing ofthe mixture is in the range of about 2250° F. to about 2380° F.
 10. Themethod of claim 1, wherein the firing of the dried mixture occurs atleast part of the time during the firing step in a reducing environment.11. The method of claim 1, wherein the clay that is provided includesfine mesh clay having a mesh of about 325 or less and the carbon that isprovided includes fine mesh carbon having a mesh of about 325 or less.12. The method of claim 1, wherein the clay is bentonite and a mixtureof volcanic ash, carbon and water is layered with the mixture ofbentonite, carbon and water, one on top of the other and the uppertemperature for the firing of the mixture is in the range of 2350° F. to2550° F.
 13. The method of claim 11, wherein the clay comprises acombination of different clays and the combination of different clayshaving a mesh of 325 or less may be layered.
 14. The method of claim 1,wherein a closed cell glass ceramic product is produced.
 15. A method ofclaim 1, wherein the clay is selected from the group of surface clays,ball clays, kaolin, shale and bentonite, the cured mixture is dried tobring the water composition in the mixture down to within the range ofabout 0.5% to about 6% by weight of the mixture, and wherein the uppertemperature for the firing of the mixture is in the range of about 2350°F. to about 2550° F.
 16. The method of claim 15, wherein the curedmixture is dried at a temperature in the range of about 850° F. to about1000° F.
 17. The method of claim 15, wherein the clay that is providedincludes fine mesh clay having a mesh of about 325 or less and thecarbon that is provided includes fine mesh carbon having a mesh of about325 or less.
 18. The method of claim 5, wherein the cured mixture isdried to bring the water composition in the mixture down to within therange of about 0.5% to about 6% by weight of the mixture.
 19. The methodof claim 18, wherein the dried mixture is fired at a temperature for aperiod of time sufficient to sinter the surface of the mixture.